1. Field of the Invention
The present invention relates generally to fluid seals, and particularly to neck seals used on rolling mill roll necks which utilize a spring as the means for applying sealing pressure to the roll neck.
2. Description of the Related Art
FIG. 1 illustrates a prior art flexible neck seal 28 of the type described in U.S. Pat. No. 4,165,881 (Salter). It includes a flexible circular seal body 30 having inner surfaces 32a, 32b adapted to be mounted in sealing engagement on the tapered section of a roll neck (not shown). The neck seal 28 is molded of a suitable resilient, rubber-like material. The seal body 30 has an exterior cylindrical surface 38 which is parallel to the rotational axis of the roll (not shown) when the neck is in its mounted position. The seal body is internally reinforced by an embedded combination of a coiled spring 34 and a steel cable 36. A pair of axially spaced circular flexible flanges 40a, 40b is integral with and extend radially outwardly from the seal body at opposite ends of the exterior cylindrical surface 38.
In a wet application, the flanges 40a, 40b of the flexible seal are each provided with circular flexible lips 42, 42b. Each flexible lip is integrally joined to and extends angularly outwardly away from the outer edge 44a, 44b of its respective supporting flange.
FIG. 2 illustrates an improved prior art neck seal as described in U.S. Pat. No. 4,586,720 (Simmons et al.) characterized by a circular shoulder 72 protruding inwardly from the tapered interior surface 74 of the seal body 12. Shoulder 72 is preferably provided with a triangular cross-sectional profile, and its apex 76 is aligned radially with the water-side flange 22. As an improvement, the apex 76 is axially offset by a distance xe2x80x9cdxe2x80x9d with respect to a reference plane P bisecting the radial outer portion of the flange 22. The offset is on the side of plane P opposite to that occupied by the water-side lip 18.
The water-side flange 22 is provided with a base portion 22a of increased thickness extending from the cylindrical exterior surface 28 of the seal body 12 to approximately the radial midpoint of the flange. The base portion has a truncated right triangular cross-sectional configuration, with the xe2x80x9chypotenusexe2x80x9d side facing the oil-side flange 24.
As a result, a shoulder 72 coacts with the tapered roll neck section (not shown) to produce a circumferential bending moment M2 acting on the seal body 12 in opposition to the circumferential bending moment M1 produced by the radial expansion of the waterside lip 18. Bending moment M2 effectively counteracts bending moment M1, with the result that the water-side flange 22 is maintained in the desired attitude perpendicular to the seal axis, and parallel to the dam (not shown).
The counteracting effect of bending moment M2 is enhanced by the increased flange stiffness at the thickened base portion 22a. The tapered configuration of the base portion 22a avoids damaging frictional contact with the dam.
A secondary benefit provided by shoulder 72 is that it provides an additional sealing line between those afforded by the water-side and oil-side lips 18, 20. This further diminishes the likelihood of fluid seepage (oil or cooling water) between the roll surface and the seal.
Now, referencing both FIGS. 1 and 2, standard in the art of most seal designs is the garter spring 80. Garter springs are generally embedded within the lip body portions of the seal, seen here in the oil-side lip 20 (FIG. 2) or 32b (FIG. 1), in order to augment the radial load provided by the resiliency of the seal lip. In these embodiments, the garter springs 80 are partially molded into the lip configuration. See U.S. Pat. No. 3,330,567 to Mercer et al. for example.
A drawback in the use of a garter spring is evident inasmuch as the garter springs can separate from the remainder of the seal as the interstitial elastomer wears. After a short time, the garter spring 80 thereby breaks through this lip, eliminating the spring seal, and the seal must be changed prematurely. Furthermore, moving or centering the garter spring 80 to be completely molded into the lip would require a difficult lip manufacturing process and would compromise accurate and consistent positioning of the garter spring 80 within the rubber mold, which can lead to variable load characteristics.
There is a need then for an improved neck seal which provides a more positive seal contact between the oil-side lip of the seal and the roll neck without the use of a garter spring.
The present invention improves on traditional neck seals by providing a metallic v-shaped spring disposed in the v-groove of a neck seal, wherein the v-groove is defined by the bottom surface of the oil-side lip and the top surface of the seal body. Also, the interior surface of the neck seal is concave throughout, whereby the above and other features of the present invention decrease manufacturing time and cost without compromising effectiveness.
An objective of the present invention is to eliminate the need for an embedded garter spring, thereby lessening the chance that the seal needs to be changed prematurely. It is further an objective of the present invention to provide a neck seal that can be easily manufactured, with no embedment of a cable or spring. It is yet another objective of the present invention to provide a seal that provides a more positive contact between the lip of the seal and the roll neck. It is further an objective of the present invention to provide a seal that retains its spring elements away from the rotating neck.
Accordingly, the neck seal is of the type having: a flexible circular seal body; a pair of axially spaced circular flexible flanges integral with and extending radially outwardly from the seal body at opposite ends of an exterior cylindrical surface; and flexible lips integrally joined to and extending angularly outwardly away from the respective flanges.
The improvement generally comprises an interior surface being concave throughout and defining the interior side of an oil-side lip extending upwards from the seal body. A portion of the lips outermost end extends radially downward to form a first stop integral with the lip. A portion of the outermost end of the seal body also extends upward from the top surface thereof to form a second stop integral with the seal body. Furthermore, a v-groove spring is disposed in a v-groove. The v-groove is defined by the inclined bottom surface of the oil-side lip and the flat top surface of the seal body such that the first and second stop retain the spring in a position conducive for a more positive seal contact between the lip of the seal and the roll neck without the use of a garter spring.